1. Field of the Invention
The present invention relates to a vibration motor and, more particularly, to a vibration motor preferably for use in incoming call notification and the like in a mobile terminal.
2. Description of the Related Art
Some mobile terminals such as mobile phones function to notify a user of an incoming call by generating vibration as well as by generating a ringtone. The vibration for incoming call notification is generated by a vibration motor that is provided in the mobile terminal. A structure in which a weight that is eccentric from a central axis rotates about the central axis so that the vibration is generated is one of vibration-generating structures provided in vibration motors.
A vibration motor that is proposed in Japanese Unexamined Patent Application Publication No. 2008-289268 is an example of vibration motors provided in mobile terminals. This vibration motor includes an eccentric weight that rotates about a shaft, and the eccentric weight rotates about the shaft so that vibration is generated. This vibration motor has an external case that forms an outer shell and a bracket that forms a bottom surface of the vibration motor, and the shaft and components constituting the vibration motor including the eccentric weight are disposed in a space which is formed by the external case and the bracket.
The bracket has a substantially disc shape and has a power supply terminal portion arrangement portion which juts radially outside from a part of a circumferential edge. The external case is a member that is configured to have an annular circumferential surface and a top surface which closes an upper end of the circumferential surface. A lower end portion of the circumferential surface of the external case is incorporated into an outer circumference of the bracket, and a part of the lower end portion of the circumferential surface of the external case is laser-welded to be fixed to the bracket. In addition, one end portion of the shaft is laser-welded to the bracket, and the other end portion of the shaft is laser-welded to the external case.
However, in a case where the external case is fixed to the bracket through the laser welding of the external case and the bracket as in the vibration motor proposed in Japanese Unexamined Patent Application Publication No. 2008-289268, the laser welding results in high manufacturing costs because equipment and running costs for the laser welding are high.